/*
 * Created on 2003-11-26
 * 
 * Alibaba.com Inc.
 * Copyright (c) 1999-2002 All Rights Reserved.
 */

package com.fancy.common.security;

import java.io.ByteArrayOutputStream;
import java.util.Random;

import javax.servlet.http.HttpServletRequest;

/**
 * base64加密
 * 
 * @author xinfeng.hu 2013-3-13下午12:15:34
 * @version 1.0.0
 * @category 杭州广桥网络技术有限公司(商业先知)
 */
@SuppressWarnings("deprecation")
public class Base64 {

	/** Don't break lines when encoding (violates strict Base64 specification) */
	public final static int DONT_BREAK_LINES = 8;

	// map 6-bit int to char
	private static final char[] chars64 = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U',
			'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
			'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' };

	// map char to 6-bit int
	private static final int[] ints64 = new int[128];
	static {
		for (int i = 0; i < 64; i++) {
			ints64[chars64[i]] = i;
		}
	}

	public static String encodeStr(String newStr) {
		if (newStr == null || newStr.length() == 0)
			return null;
		String encoded = encode(newStr.getBytes());
		if (encoded == null || encoded.length() == 0)
			return null;

		return java.net.URLEncoder.encode(encoded);

	}

	public static String decodeStr(String newStr, HttpServletRequest req) {
		if (req == null || !("Y".equals(req.getParameter("encode"))))
			return newStr;
		if (newStr == null || newStr.length() == 0)
			return null;
		String urlDecode = java.net.URLDecoder.decode(newStr);

		byte[] decode = decode(urlDecode);
		if (decode == null || decode.length == 0)
			return null;

		return (new String(decode));
	}

	/** Convert byte array into Base64 string */
	public static final String encode(byte[] unencoded) {
		// Take 24-bits from three octets, translate into four encoded chars.
		// If necessary, pad with 0 bits on the right at the end
		// Use = signs as padding at the end to ensure encodedLength % 4 == 0
		if (unencoded == null || unencoded.length == 0)
			return null;

		ByteArrayOutputStream out = new ByteArrayOutputStream((int) (unencoded.length * 1.37));
		int byteCount = 0;
		int carryOver = 0;

		for (int i = 0; i < unencoded.length; i++) {
			int bc = (byteCount % 3);
			byte b = unencoded[i];
			int lookup = 0;

			// First byte use first six bits, save last two bits
			if (bc == 0) {
				lookup = (b >> 2) & 0x3F;
				carryOver = b & 0x03; // last two bits
				out.write(chars64[lookup]);
			} else if (bc == 1) {
				// Second byte use previous two bits and first four new bits,
				// save last four bits
				lookup = ((carryOver << 4) | ((b >> 4) & 0x0F));
				carryOver = b & 0x0F; // last four bits
				out.write(chars64[lookup]);
			} else if (bc == 2) {
				// Third byte use previous four bits and first two new bits,
				// then use last six new bits
				lookup = ((carryOver << 2) | ((b >> 6) & 0x03));
				out.write(chars64[lookup]);

				lookup = b & 0x3F; // last six bits
				out.write(chars64[lookup]);
				carryOver = 0;
			}
			byteCount++;
		}

		if (byteCount % 3 == 1) { // one leftover
			int lookup = (carryOver << 4) & 0xF0;
			out.write(chars64[lookup]);
			out.write('=');
			out.write('=');
		} else if (byteCount % 3 == 2) { // two leftovers
			int lookup = (carryOver << 2) & 0x3C;
			out.write(chars64[lookup]);
			out.write('=');
		}
		return out.toString();
	}

	/** Decode Base64 string back to byte array */
	public static final byte[] decode(String encoded) {
		if (encoded == null || encoded.length() == 0)
			return null;

		byte[] bytes = encoded.getBytes();

		ByteArrayOutputStream out = new ByteArrayOutputStream((int) (bytes.length * 0.67));
		int byteCount = 0;
		int carryOver = 0;

		DECODE_LOOP: for (int i = 0; i < bytes.length; i++) {
			int ch = bytes[i];

			// Read the next non-whitespace character
			// if (Character.isWhitespace((char)ch))
			// continue;

			// The '=' sign is just padding; geffective end of stream
			if (ch == '=')
				break DECODE_LOOP;

			// Convert from raw form to 6-bit form
			int newbits = ints64[ch];

			int bc = (byteCount % 4);
			if (bc == 0) {
				// First char save all six bits, go for another
				carryOver = newbits & 0x3F;
			} else if (bc == 1) {
				// second char use 6 previous bits and first 2 new bits
				int data = ((carryOver << 2) + ((newbits >> 4) & 0x03));
				out.write(data);
				carryOver = newbits & 0x0F; // save 4 bits
			} else if (bc == 2) {
				// Third char use previous four bits and first four new bits,
				// save last two bits
				int data = ((carryOver << 4) + ((newbits >> 2) & 0x0F));
				out.write(data);
				carryOver = newbits & 0x03; // save 2 bits
			} else if (bc == 3) {
				// Fourth char use previous two bits and all six new bits
				int data = ((carryOver << 6) + (newbits & 0x3F));
				out.write(data);
				carryOver = 0;
			}
			byteCount++;
		}

		return out.toByteArray();
	}

	/**
	 * UNIT TEST
	 */
	public static String str = "This is a test";

	public static void main(String[] args) throws Exception {
		// test1(args);
		test1(new String[] { "dfdfd" });
	}

	private static void test1(String[] args) {
		if (args.length > 0) {
			str = args[0];
		}

		printString("Start", str);
		String encoded = Base64.encode(str.getBytes());
		printString("Encoded", encoded);
		String decoded = new String(Base64.decode(encoded));
		printString("Decoded", decoded);
		System.err.println("** " + (decoded.equals(str) ? "SUCCESS" : "FAILURE"));
	}

	public static void test2(String[] args) throws Exception {
		int count = 30;
		if (args.length > 0) {
			count = Integer.parseInt(args[0]);
		}
		if (count <= 0)
			count = 30;

		byte[] data = new byte[count];
		Random rand = new Random();
		rand.nextBytes(data);
		printBytes("Source", data);

		String encoded = Base64.encode(data);
		printString("Encoded", encoded);

		byte[] bin = Base64.decode(encoded);
		printBytes("Final", bin);

		if (bin.length != data.length) {
			System.err.println("::FAILURE::");
			return;
		}

		for (int i = 0; i < bin.length; i++) {
			if (bin[i] != data[i]) {
				System.err.println("::FAILURE::");
				return;
			}
		}
		System.err.println("::SUCCESS::");
	}

	private static void printString(String prompt, String s) {
		System.err.println("** " + prompt + "='" + s + "' (length=" + s.length() + ")");
	}

	public static void printBytes(String prompt, byte[] data) {
		System.err.print("** " + prompt + " = [");
		for (int i = 0; i < data.length; i++) {
			String sep = ",";
			if (i == 0)
				sep = "";
			System.err.print(sep + data[i]);
		}
		System.err.println("] (length=" + data.length + ")");
	}

}
